Cam mounting means for zigzag sewing machines



Oct. 9, 1962 R. E- JOHNSON 3,057,311

CAM MOUNTING MEANS FOR ZIGZAG SEWING MACHINES Filed Jan. 25. 1960 WITNESS 5 v PZLZQKZ/ P2 y ATTORNEY United States Patent Ofilice 3,057,31 l Patented Oct. 9, 1962 11 CAM MOUNTING MEANS FUR ZEGZAG SEWING MAQMNES Ralph E. Johnson, Mountainside, N..l., assignor to The i i l Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Filed Jan. 25, 1969, Ser. No. 4,312 Claims. (Cl. 112-158) The present invention relates to zigzag sewing machines and particularly to a zigzag sewing machine of the type having a replaceable stitch pattern cam for imparting lateral vibration to the needle bar and thereby defining an ornamental stitch pattern.

The object of this invention is to provide, in such a sewing machine, an improved and simplified mounting for the stitch pattern cam that is economical, and provides an efiicient, dependable, and durable construction. It is a specific object of this invention to provide a construction for mounting and driving a stitch pattern cam in a zigzag sewing machine, wherein the elements can be preassembled and inserted into the machine as a unit and wherein manufacturing and assembly has been simplified in that, for the most part, they are not critical.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a fragmentary top plan view of the bracket arm of a sewing machine embodying the present invention and in which the top cover plate has been removed.

FIG. 2 is a sectional view taken substantially on the line 22 of FIG. 1.

FIG. 3 is a detail sectional view taken substantially on the line 33 of FIG. 2.

FIG. 4 is a detail sectional view taken substantially on the line 44 of FIG. 2.

The present invention is herein illustrated as embodied in the zigzag sewing machine forming the subject matter of the copending United States patent application of Johnson, Serial No. 4,430, filed January 25, 1960, wherein the machine is fully disclosed and to which reference may be had for a more complete understanding thereof.

With reference to the drawings, there is illustrated the bracket arm 1 of a sewing machine having a rotary main shaft 2 journalled longitudinally thereof. Mounted in the bracket arm 1 in a bearing boss 3 is a vertical axis stud 4. The stud 4 has a mounting portion 5 at its lower end that is received within a bore 6 in the boss 3 and in which it is secured by a set screw 7. Above the mounting portion 5 of the stud 4 there is an intermediate portion 8 that is enlarged diametrically and disposed eccentrically relatively to the mounting portion 5. Between the mounting portion 5 and the intermediate portion 8, the stud 4 is formed with a groove 9 that reduces the periphery of the stud 4 to less than the diameter of the mounting portion 5. The groove 9 is located so that the shoulder 10 which defines the bottom edge of the groove 9 and the top edge of the mounting portion 5 is generally aligned with the top surface 11 of the boss 3 when assembled, which surface is accurately machined and constitutes a position ing surface. The width of the groove 9 is not critical but is made wide enough so that the shoulder 12, which defines the top edge of the groove 9 and the bottom edge ing for a significant endwise movement of the stud 4 downwardly from the designed position before the shoulder 12 contacts the surface 11. Above the intermeditae portion 8, the stud 4 has a reduced diameter upper portion 13 concentric with the intermediate portion 8 and having a screw driver slot 14 in the upper end thereof.

Journaled on the intermediate portion 8 of the stud 4 is a tubular cam shaft 15 having a central bore 16 that receives the intermediate portion 8 and defining an annular side wall. The lower end of the cam shaft 15 is in bearing engagement with the surface 11 of the boss 3. There is provided a pair of meshing gears for imparting rotation to the cam shaft 15 comprising a worm wheel 17 formed on the lower end of the cam shaft 15 that meshes with a worm 18 on the main shaft 2.

On the upper end of the cam shaft 15 there is a flange 19 having a seat 20 formed on the upper face thereof for receiving a stitch pattern cam 21 having a peripheral pattern surface 22. The cam 21 is clamped on the seat 20 by a thumb screw 23 having an enlarged head 24, an externally threaded shank 25 that is screwed into the internally threaded upper portion of the bore 16 in the cam shaft 15, and a central bore 26 through which the reduced upper portion 13 of the stud 4 extends. The cam 21 is positioned angularly on the seat 20 by a pin 27 extending through the flange 19 on an axis parallel to the stud 4 and secured therein by a set screw 28. The pin 27 extends above the seat 20 and enters a radial slot 29 in the cam 21.

Below the flange 19 the cam shaft 15 is provided with a second flange 30 which, below the pin 27, has a seat 31 formed on the upper surface thereof for receiving a key 32. A horizontal slot 33 is cut through the side wall of the cam shaft 15, the slot 33 having the bottom edge thereof in a plane with the seat 31 extending substantially one-half the distance around the cam shaft. In the area opposite the slot 33, there is formed in the periphery of the intermediate portion 8 of the stud 4 an annular groove 34. The key 32 extends through the slot 33 and into the groove 34 and has an inner edge 35 formed to embrace the stud 4 at the base of the groove 34. The key 32 is held on the seat 31 by the pin 27 which has a reduced diameter lower end 36 entering a hole 37 in the key.

The cam 21 is designed to be interchangeable with similar cams having a different periphreal cam surface, such as the surface 22, which will produce a different ornamental stitch pattern. To replace the cam 21, the clamping screw 23 is backed off, the cam removed, a different cam substituted, and the clamping screw 23 replaced. In effect, the clamping screw 23 is journaled on the reduced upper portion 13 of the stud 4- which serves to align the threads of the screw with those in the bore 16, thus facilitating replacing the clamping nut.

In the usual manner, the top of the bracket arm 1 is open and is adapted to be closed by a top cover plate 38. To obtain accessibility for changing the cam 21, the cover plate has a cut-out 39 exposing the cam through the cover plate 38, and a hinged plate 40 is provided on the cover plate and overhanging the cam 21.

When the present mechanism is assembled in the machine, it is first preassembled as a unit on the stud 4. The cam shaft 15 is placed on the stud 4 and the key 32 is placed on the seat 31 and inserted through the slot 33 and into the groove 34 in the stud 4. The pin 27 is then inserted and, with the end 36 thereof seated in the hole 37 of the key, it is locked by the set screw 28. The cam 21 and the clamping screw 23 may be placed on the cam shaft 15 at this time or it may be placed thereon at a later time. The unit is then inserted into the machine with the mounting portion 5 of the stud 4 entering the bore 6 in the boss 3. The assembly is moved downwardly until the bottom of the cam shaft 15 engages the surface 11 of the boss 3 and thereafter, the stud 4 is moved downwardly until the key 32 engages the upper edge of the groove 34. By means of the screw driver slot 14, the stud 4 is turned which, through the eccentricity of the intermediate portion 8 relatively to the mounting portion 5, adjusts the axis of the cam shaft 15 toward and away from the main shaft 2 to obtain the desired meshing relation between the worm 18 and worm wheel 17. The stud 4 is then locked by means of the set screw 7. The cam shaft 15 is held against endwise movement on the stud 4 by the surface 11 and the key 32.

The primary advantage of the construction in accordance with this invention is that the parts have reduced tolerance requirements which reduce manufacturing expenses, and can be primarily assembled by inexpensive labor. The initial assembly of the unit is simple and not critical in any respect. The only alignment that is necessary is at the time that the unit is assembled into the machine and this is only to adjust the axis of the cam shaft 15 relatively to the axis of the main shaft 2, which is provided by the eccentric portion 8 of the stud 4. The only other alignment that is necessary is the vertical positioning of the cam shaft 15 to locate the worm wheel 17 and this is accomplished by the surface 11. The groove can accommodate wide variations in manufacturing tolerances to take up end play of the cam shaft on the stud 4. The dimension of the groove 34 also is not critical, but preferably is made wide enough to facilitate insertion of the key 32.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus described the nature of the invention, what I claim herein is:

1. In a zigzag sewing machine having a frame, a stud mounted in said frame, a tubular cam shaft having an annular side wall and a central bore for receiving said stud and for journalling said cam shaft on said stud, means on said frame for positioning said cam shaft endwise relatively to said stud, means for imparting rotation to said cam shaft, said cam shaft having a cam receiving seat for supporting an ornamental stitch pattern cam, means for [releasably clamping a cam on said seat, and means for positioning and securing said cam shaft on said stud comprising a key carried by said cam shaft, said cam shaft having a slot normal to the axis of said stud and extending through the side wall thereof, said stud having an annular groove in the periphery thereof and communicating with said slot, said key extending through said slot and into said groove, and means carried by said cam shaft for releasably holding said key in said slot and said groove.

2. In a zigzag sewing machine having a frame, a boss in said frame having a positioning surface and a bore intersecting said positioning surface, a stud mounted in said bore for endwise adjustment, means for releasably securing said stud in said bore in adjusted position, a tubular cam shaft having an annular side wall and a central bore for receiving said stud and for journalling said cam shaft on said stud, said cam shaft being positioned on said stud with the end thereof in bearing engagement with said positioning surface, means for impar-ting rotation to said cam shaft, said cam shaft having a cam receiving seat for supporting an ornamental stitch pattern cam, means for releasably clamping a cam on said seat, said stud having an annular groove in the periphery thereof and said cam shaft having a slot normal to the axis of said stud and extending through the annular side Wall thereof and communicating with said groove, a key carried by said cam shaft and extending through said slot and into said groove, and means carried by said cam shaft for releasably holding said key in tubular cam shaft having an annular side wall and a central bore for receiving said stud and for journalling said cam shaft on said stud, said cam shaft being positioned on said stud with the end thereof in bearing engagement with said positioning surface, means for imparting rotation to said cam shaft, said cam shaft having a cam receiving seat for supporting an ornamental stitch pattern cam, means for releasably clamping a cam on said seat, a flange on said cam shaft having a seat, said cam shaft having a slot normal to the axis of said stud and extending through the annular side Wall thereof, said stud having an annular groove in the periphery thereof and communicating with said slot, a key mounted on said seat and extending through said slot into said groove, and means carried by said cam shaft for releasably holding said key in said slot and said groove.

4. In a zigzag sewing machine having a frame, a boss in said frame having a positioning surface and a bore intersecting said positioning surface, a stud mounted in said bore for endwise adjustment and projecting from said positioning surface, means for releasably securing said stud in said bore in adjusted position, a tubular cam shaft having an annular side wall and a central bore for receiving said stud and for journalling said cam shaft on said stud, said cam shaft being positioned on said stud with the end thereof in bearing engagement with said positioning surface, means for imparting rotation to said camshaft, a flange on said cam shaft having a cam-receiving seat formed to receive an ornamental stitch pattern cam, a screw for clamping a cam on said seat, a pin slidably extending through said flange and having an end project-ing from said cam-receiving seat for positioning a cam angularly on said cam-receiving seat, said cam shaft having a key-receiving seat, and having a slot extending through the annular side wall thereof and intersecting said key-receiving seat, said stud having an annular groove in the periphery thereof and communicating with said slot, a key mounted on said key-receiving seat and extending through said slot into said groove, said pin cooperating with said key for holding the same in assembled relation, and means for releasably securing said pin in position.

5. In a zigzag sewing machine having a frame, a boss in said frame having a positioning surface and a bore intersecting said positioning surface, a stud having a mounting portion at the one end, an intermediate portion, and a reduced end portion at the other end, said mounting portion being received in said bore for endwise adjustment, means for releasably securing said mounting portion in said bore in adjusted position, a tubular cam shaft having an annular side wall and a central bore for receiving the intermediate portion of said stud and for journalling said cam shaft on said intermediate portion, said cam shaft being positioned on said stud with the end thereof in bearing engagement with said positioning surface, means for imparting rotation to said cam shaft, a flange on said cam shaft having a camreceiving seat formed to receive an ornamental stitch pattern cam, a screw having a central bore for receiving the reduced end portion of said stud and an externally threaded shank threaded into the end of said cam shaft for clamping a cam on said cam-receiving seat, a pin slidably extending through said flange and having an end projecting from said cam-receiving seat for positioning a cam angularly on said cam-receiving seat, said cam shaft having a key-receiving seat, and having a slot extending through the annular side wall thereof and intersecting said key-receiving seat, said stud having an annular groove in the periphery thereof and communicating with said slot, a key mounted on said key-receiving seat and extending through said slot into said groove, said pin cooperating with *said key for holding the same in assembled relation, and means for releasably securing 5 said pin in position.

References Cited in the file of this patent UNITED STATES PATENTS 294,632 Kennedy et a1. Mar. 4, 1884 10 6 Knupp et a1. Jan. 23, 1906 Clouse Jan. 23, 1912 Davis Feb. 26, 1918 Beede et a1. Aug. 15, 1944 Johnson Dec. 2, 1958 Gegauf Aug. 25, 1959 Vigorelli Sept. 29, 1959 FOREIGN PATENTS Belgium Feb. 23, 1955- 

